JP2007185275A - Residual gas removal method in gas sterilization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the removal of the residual gas in a shorter time concerning a residual gas removal method for removing the gas left in an object subjected to the gas sterilization treatment in the gas sterilization for sterilizing the object such as a medical tool using a sterilization gas. <P>SOLUTION: In the residual gas removal method in the gas sterilization for removing the gas left in the object subjected to the gas sterilization treatment, the object subjected to the gas sterilization treatment is placed in a closed space and undergoes the following processes: the steam soaking process for supplying the steam into the closed space under a negative pressure below the atmospheric pressure and held for a prescribed period of time to get the steam soaked into the object and the decompression exhaust process which follows the steam soaking process for exhausting the steam under a reduced pressure within the closed space. The steam soaking process and the decompression exhaust process are repeated a plurality of times. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a residual gas removal method for removing a gas remaining in an object to be sterilized in gas sterilization in which the object to be sterilized such as a medical device is sterilized using a sterilization gas.

  As a gas sterilization method, a method using ethylene oxide gas (hereinafter referred to as EOG) as a sterilization gas is known. In this gas sterilization method, it is necessary to remove the gas remaining in the article to be sterilized after the gas sterilization treatment. As a method for removing the residual gas, a method called aeration in which the removal is performed by repeatedly supplying and discharging air into the treatment tank is generally used. According to this method, it takes a long time of, for example, 8 hours or more to reduce the residual gas concentration of an object to be sterilized to 10 ppm or less, and it takes more than half a day from the start to the end of the sterilization operation.

  As a result of pursuing the cause, the inventors of this application have found that EOG adsorbed inside the article to be sterilized (mainly plastic material) is released to the outside only by internal diffusion, and the removal rate becomes slow. This led to the creation of the invention of the application.

  Aside from the researches by the inventors, a method for shortening such residual gas removal time is proposed in Patent Document 1. In this method, after the gas sterilization is completed, the vacuum pump is continuously operated to discharge the gas in the treatment tank, and the open / close valve provided in the middle of the steaming line is repeatedly opened and closed, thereby remaining gas. The removal is performed.

  However, in this method, in order to continuously operate the vacuum pump, since much of the steam supplied into the processing tank is exhausted to the outside of the processing tank in a short time, the penetration of the steam into the sterilized material Is not done effectively. For this reason, the gas remaining inside the article to be sterilized cannot be removed effectively.

JP-A-2-63461

  The problem to be solved by the present invention is to remove residual gas in a short time.

  The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is a residual gas removal method in gas sterilization that removes gas remaining in an object to be sterilized after gas sterilization. A vapor infiltration step in which the sterilized material that has been subjected to gas sterilization is placed in a sealed space, steamed into the sealed space under a negative pressure less than atmospheric pressure, and held for a predetermined time to infiltrate the vapor into the sterilized material; And a reduced pressure exhaust stroke which is performed after the vapor permeation step and exhausts the inside of the sealed space under reduced pressure.

  Furthermore, the invention described in claim 2 is characterized in that, in claim 1, the steam permeation step and the vacuum exhaust stroke are repeated a plurality of times.

  According to this invention, the residual gas in the article to be sterilized can be effectively removed, and the time required for removing the residual gas can be shortened.

  Next, an embodiment of the present invention will be described. Embodiments of the present invention include a gas sterilization apparatus that removes residual gas from an object to be sterilized, and a sterilization gas removal apparatus that is provided separately from the gas sterilization apparatus and removes residual gas from the object to be sterilized by the gas sterilization apparatus. Applies to

  An embodiment of the present invention is a residual gas removal method in gas sterilization that removes gas remaining in an object to be sterilized by sterilization gas such as EOG. A vapor infiltration step in which steam is infiltrated into an object to be sterilized by being steamed into the enclosed space under a negative pressure less than atmospheric pressure and kept for a predetermined time, and the enclosed space is performed after the vapor infiltration step. A method for removing residual gas in gas sterilization, comprising a reduced pressure exhaust process for exhausting the inside of the interior under reduced pressure.

  In this embodiment, first, the object to be sterilized is gas sterilized. Next, a steam infiltration process is performed. In this steam infiltration process, an object to be sterilized by gas sterilization is placed in a sealed space, and steam is supplied (supplied) to the sealed space under a negative pressure (also referred to as negative pressure) below atmospheric pressure. The steaming state is maintained for a predetermined time. At this time, no vacuum exhaust from the sealed space and no exhaust from the sealed space are performed. By maintaining this steam supply state for a predetermined time, the vapor in the sealed space penetrates into the sterilized material, and the residual gas in the sterilized material dissolves in the permeated vapor or condensed water. Next, a vacuum exhaust stroke is performed. In this decompression exhaust process, the inside of the sealed space is decompressed by decompression means such as a vacuum pump, and the internal gas is discharged. By this decompression exhaust process, the condensed water that has penetrated into the object to be sterilized and absorbed the residual gas is vaporized, and the residual gas is discharged out of the sealed space together with the vaporized vapor. In this way, the gas remaining on the object to be sterilized is removed.

  Next, components of this embodiment will be described. The article to be sterilized is a medical device and the like, and is not limited to a specific one. However, the present invention is preferably implemented for an article to be sterilized made of a plastic material. The gas sterilization process is performed by a known gas sterilization apparatus, and the sterilization method is not limited to a specific method. In addition, the gas sterilization treatment can be configured to be performed in the sealed space at atmospheric pressure or positive pressure (which can be referred to as positive pressure) equal to or higher than atmospheric pressure.

  The sealed space is formed by a treatment tank of a gas sterilization apparatus or a sterilization gas removal apparatus. This treatment tank is connected to the outside by an opening with a door for taking in and out the object to be sterilized, a steam supply line, a return pressure line, and a vacuum exhaust line, but by closing the opening and closing a valve provided in each line A sealed space can be formed.

  In the vapor permeation step, a gas sterilized article to be sterilized is placed in the sealed space, and the inside of the sealed space is depressurized to a set negative pressure (first set pressure). Steaming (humidification), that is, a process of supplying a predetermined amount of steam into the sealed space and maintaining the steam supply state for a predetermined time, thereby allowing the steam to penetrate into the sterilized object. The predetermined time is determined by experimentally measuring the degree of vapor penetration into the article to be sterilized.

  Further, the reduced pressure exhaust process is a process that is performed after the vapor infiltration step, stops steaming, and exhausts the sealed space by reducing the pressure. This pressure reduction is performed until the inside of the sealed space becomes a second set pressure lower than the first set pressure. This decompression exhaust process is a process of evaporating the condensed water that has penetrated into the sterilized material and dissolved the residual gas, and can be referred to as an evaporation exhaust process.

After the decompression process, the vapor permeation step and the decompression process are performed one or more times as necessary.

  Next, an embodiment of a residual gas removing apparatus in which the residual gas removing method of the present invention is implemented will be described.

  The residual gas removing device includes a processing tank for storing an object to be sterilized, a steaming means for steaming (or humidifying) the processing tank, a decompression means for decompressing the inside of the processing tank, A pressure return means for returning the pressure in the treatment tank; and a control means for controlling the steam supply means, the pressure reduction means, and the pressure return means, and the control means is provided in the treatment tank in a sealed state. A vapor infiltration step in which steam is supplied to the treatment tank as a negative pressure less than atmospheric pressure and held for a predetermined time, and a reduced pressure exhaust process is performed after the vapor infiltration process to decompress and exhaust the inside of the treatment tank. is there.

  According to the embodiment of the residual gas removing apparatus, the effects that can be obtained by the embodiment of the residual gas removing method can be achieved.

  This residual gas removing device can also be used as a gas sterilizer, and in the case of using it as a gas sterilizer, is provided with a gas supply means for supplying a sterilizing gas into the treatment tank.

  The steaming means includes a steaming line (piping) having one end connected to the steam generator and the other end connected to the treatment tank, and a steaming valve provided in the middle of the steaming line. . The steam supply valve is an electromagnetic valve that can only be opened and closed, but can be an adjustment valve whose opening degree can be adjusted as necessary.

  The decompression means includes an exhaust line (pipe) connected to the treatment tank, a decompressor provided in the middle of the exhaust line, a check valve for preventing a back flow in the treatment tank direction, and a sealed state of the treatment tank. And an on-off valve for holding the valve. The decompressor is configured by combining a heat exchanger that condenses steam, provided on the upstream side of the decompressor, if necessary, in combination with one or more of a steam ejector, a vacuum pump, and a water ejector. be able to. The on-off valve may be a valve whose opening degree can be adjusted.

  The return pressure means has one end connected to the treatment tank, a return pressure line (pipe), an air purification filter provided in the middle of the return pressure line, a return pressure valve, and a reverse flow from the treatment tank to the atmosphere. And a check valve. The return pressure valve is an electromagnetic valve that can only be opened and closed, but can be an adjustment valve whose opening degree can be adjusted as necessary.

  The control means inputs a signal from a pressure detection means for detecting the pressure in the processing tank, controls the steam supply means and the pressure reducing means, and at least the steam permeation step and the pressure reduction exhaust stroke. A control procedure for removing residual gas is performed.

  Hereinafter, specific examples of the residual gas removing method of the present invention will be described in detail with reference to the drawings. FIG. 1 is a time-pressure characteristic diagram in the treatment tank for explaining the embodiment, and FIG. 2 is a view for explaining a schematic configuration of a gas sterilization apparatus 1 that implements the residual gas removing method of the embodiment.

  First, the gas sterilizer 1 will be described with reference to FIG. This gas sterilization apparatus 1 is an apparatus having a gas sterilization function and a residual gas removal function for removing gas remaining in an object to be sterilized.

The gas sterilization apparatus 1 includes a sterilization object to be sterilized and a processing tank 2 for storing the sterilized object to be sterilized, and a gas supply means 3 for supplying a sterilization gas (EOG) to the processing tank 2,
Steaming means 4 for supplying saturated steam (hereinafter simply referred to as steam), decompression means 5 for decompressing the inside of the treatment tank 2, decompression means 6 for decompressing the inside of the treatment tank 2, and the steaming Means 4 and a controller 7 as control means for controlling the decompression means 5 and the decompression means 6 are provided as main parts.

  The said processing tank 2 is equipped with the door (illustration omitted) which can be opened and closed, and defines the sealed space of this invention.

  One end of the gas supply means 3 is connected to an EOG supply source (not shown) such as a cylinder, and the other end is connected to the processing tank 2. A gas supply line 8 is provided in the middle of the gas supply line 8. And a gas supply valve 9.

  The steam supply means 4 includes a steam supply line 10 having one end connected to a steam generator (not shown) and the other end connected to the treatment tank 2 and a steam supply valve 11 provided in the middle of the steam supply line 10. Consists of including.

  The decompression means 5 includes an exhaust line 12 connected to the processing tank 2, a vacuum pump 13 as a decompressor provided in the middle of the exhaust line 12, and a first check that prevents backflow in the direction of the processing tank 2. On-off valve 15 comprising a valve 14 and an electromagnetic valve provided to keep the processing tank 2 hermetically sealed in the steam permeation step, that is, to prevent steam from leaking from the processing tank 2 through the exhaust line 12. It is comprised including. The exhaust line 12 is connected to an EOG processing device 16.

  The return pressure means 6 has a return pressure line 17 having one end connected to the treatment tank 2, an air purification filter 18 provided in the middle of the return pressure line 17, a return pressure valve 19, and the treatment tank 2 toward the atmosphere. And a second check valve 20 for preventing the backflow.

  Further, the controller 6 inputs a signal from a pressure sensor 21 as pressure detecting means for detecting the pressure in the processing tank 2, and supplies the gas supply valve 9 of the gas supply means 3 and the steam supply means 4. The steam supply valve 11, the opening / closing valve 15 of the decompression means 5, the vacuum pump 13, and the return pressure valve 19 of the return pressure means 6 are controlled to execute a previously stored processing procedure.

  As shown in FIG. 1, this processing procedure includes a gas sterilization process for gas sterilizing an object to be sterilized contained in the processing tank 2, and a cleaning process (referred to as an aeration process) for mainly discharging the gas in the processing tank 2. A residual gas removal step (which can be referred to as a humidified aeration step) that mainly removes residual gas remaining in the article to be sterilized, the cleaning step, and the pressure-reducing step of the treatment tank 2 Are sequentially performed.

  The operation of this embodiment will be described below with reference to FIGS.

(Preparation process)
First, an object to be sterilized is accommodated in the treatment tank 2 and the treatment tank 2 is sealed. Thereafter, the on-off valve 5 and the return pressure valve 19 are opened, and the vacuum pump 13 is operated. Thereby, the air in the processing tank 2 is discharged from the exhaust line 12 while introducing aseptic air (hereinafter referred to as sterile air) obtained from the return pressure line 17 through the filter 18. As a result, the inside of the treatment tank 2 is replaced with aseptic air.

(Sterilization process)
In this state, the inside of the processing tank 2 is heated to a predetermined temperature by a heating means (not shown), and then the air in the processing tank 2 is discharged from the exhaust line 12. Next, steam is supplied from the steam supply means 4 into the treatment tank 2 to obtain an appropriate humidity suitable for gas sterilization. In this state, the gas supply valve 9 is opened to supply EOG from the gas supply line 8 into the processing tank 2, and then sterilization is performed by holding for a predetermined time. After performing this sterilization process for a predetermined time, with the gas supply valve 9 and the return pressure valve 19 closed, the open / close valve 15 is opened and the vacuum pump 13 is operated to set a first set pressure lower than atmospheric pressure. A decompression step (final vacuum step) for reducing the pressure to P1 is performed. Thereafter, the process proceeds to a cleaning process.

(Washing process)
In the cleaning step, the return pressure valve 19 is opened and the vacuum pump 13 is operated with the open / close valve 15 open, and a second set pressure P2 higher than the first set pressure P1 and lower than the atmospheric pressure is set. By controlling so as to become, the EOG in the processing tank 2 is discharged out of the processing tank 2 through the exhaust line 12. In this cleaning step, the operation of the pressure-reducing means 6, that is, the opening of the pressure-reducing valve 19 and the operation of the pressure-reducing means 5, that is, the operations of the on-off valve 15 and the vacuum pump 13 are performed alternately. It can comprise so that EOG in the tank 2 may be discharged | emitted.

(Residual gas removal process)
The residual gas removal step includes a vapor permeation step and a vacuum exhaust stroke performed thereafter.

(Vapor penetration process)
The vapor infiltration step includes a vacuum step for making the inside of the treatment tank 2 a negative pressure, a humidification step for humidifying the inside of the treatment tank 2, and a humidification keeping step for keeping the humidification state with the treatment tank 2 sealed. including.

  First, a vacuum process is performed in which the return pressure valve 19, the steam supply valve 11, and the gas supply valve 9 are closed and the pressure reducing means 5 is operated to reduce the pressure in the processing tank 2 to the first set pressure P1.

  Then, the operation of the decompression unit 5 is stopped, the steam supply unit 4 is operated, and a humidification step of supplying a predetermined amount of steam into the processing tank 2 is performed.

  Then, the humidification keeping step of closing the steam supply valve 11 and maintaining (maintaining) this state at the third set pressure P3 slightly higher than the first set pressure is performed for a predetermined time (for example, 10 minutes). Degree) to do. In this embodiment, control for holding at the third set pressure P3 is not performed, but control for holding can be performed.

  This steam permeation step is configured to permeate the necessary steam into the sterilized object while the inside of the treatment tank 2 is kept in a sealed state and at a negative pressure. As a result, the supplied steam penetrates to the inside of the article to be sterilized. The permeated vapor exists in the form of condensed water and dissolves and absorbs EOG remaining inside.

(Decompression exhaust stroke)
After the vapor permeation step, a vacuum exhaust stroke is performed in which water or vapor that has absorbed EOG is discharged out of the treatment tank 2. In this depressurization exhaust stroke, the supply gas valve 9, the steam supply valve 11 and the return pressure valve 19 are closed and the depressurization means 5 is operated, so that the pressure in the processing tank 2 is lower than the first set pressure P1. The pressure is reduced to the set pressure P4. The water or steam that has absorbed EOG by this pressure reduction is effectively discharged out of the treatment tank 2 through the exhaust line 12. As a result, EOG remaining on the sterilized material is removed. The removed EOG is rendered harmless by the EOG processing device 16.

As shown in FIG. 1, the residual gas removal step is repeatedly performed a predetermined number of times such as a first residual gas removal step → second residual gas removal step →. In the second residual gas removal step, the humidification step, the humidification keeping step, and the reduced pressure exhaust process are sequentially performed as in the first residual gas removal step. The second residual gas removal step differs from the first residual gas removal step in the following two points. First, in the second residual gas removal step, the first decompression step of the first residual gas removal step is omitted. This is because the inside of the processing tank 2 is depressurized to the fourth set pressure by the final depressurization exhaust stroke in the first residual gas removal step. Next, in the second residual gas removal step, the humidification keeping step and the reduced pressure exhaust process are performed at a lower set pressure than in the first residual gas removal step. By this second residual gas removal step, the gas remaining in the sterilized material that could not be removed in the first residual gas removal step is removed.

  When the residual gas removal step is completed, a cleaning step similar to the cleaning step is continuously performed for a predetermined time. Thereafter, the return pressure valve 19 is opened, the inside of the processing tank 2 is returned to atmospheric pressure, the entire processing process is terminated, and the sterilized material from which the residual EOG is removed from the processing tank 2 is taken out.

  The present invention is not limited to the first embodiment, and can be a residual gas removal method of the second embodiment shown in FIG. In the second embodiment, the description of the same configuration as that of the first embodiment is omitted, and only a different configuration will be described below. The second embodiment is that a return pressure process is provided between the humidification keeping process and the reduced pressure exhaust process. In this return pressure step, the return pressure valve 19 is opened, the inside of the processing tank 2 is returned to the fifth set pressure P5 lower than the second set pressure P2 and higher than the third set pressure, and the process tank 2 is recovered. Introduce sterile air into it. In this embodiment, the fifth set pressure value can be changed.

It is a time-pressure characteristic view explaining Example 1 of this invention. It is a figure explaining the schematic structure of the gas sterilizer which implemented the same Example 1. FIG. It is a time-pressure characteristic view explaining Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas sterilizer 2 Processing tank 3 Gas supply means 4 Steaming means 5 Depressurization means 6 Restore pressure means 7 Controller

Claims (2)

A residual gas removal method in gas sterilization for removing gas remaining in an object to be sterilized subjected to gas sterilization,
A vapor infiltration step in which an object to be sterilized after gas sterilization is placed in a sealed space, steamed into the sealed space under a negative pressure of less than atmospheric pressure and held for a predetermined time,
A method for removing residual gas in gas sterilization, comprising: a reduced pressure exhaust process that is performed after the vapor permeation step and performs reduced pressure exhaust of the sealed space.   The method for removing residual gas in gas sterilization, wherein the vapor permeation step and the vacuum exhaust stroke are repeated a plurality of times.

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